Lines Matching full:block
45 consumes an entire block group, though mke2fs tries to put it in the
74 or a block revocation list. A finished transaction always ends with a
85 will be an ext4 super block in the usual place, with a matching UUID.
86 The journal superblock will be in the next full block after the
105 Block Header
108 Every block in the journal starts with a common 12-byte header
126 - Description of what this block contains. See the jbd2_blocktype_ table
131 - The transaction ID that goes with this block.
135 The journal block type can be any one of:
144 - Descriptor. This block precedes a series of data blocks that were
147 - Block commit record. This block signifies the completion of a
154 - Block revocation records. This speeds up recovery by enabling the
157 Super Block
160 The super block for the journal is much simpler as compared to ext4's.
186 - Journal device block size.
194 - First block of log information.
206 - Block number of the start of log. Contrary to the comments, this field
232 super block at mount time.
240 - Location of dynamic super block copy. (Not used?)
265 - Block number of the head (first unused block) of the journal, only
307 - Journal has block revocation records. (JBD2_FEATURE_INCOMPAT_REVOKE)
309 - Journal can deal with 64-bit block numbers.
315 metadata block gets its own checksum, and the block tags in the
320 v2, but the journal block tag size is fixed regardless of the size of
321 block numbers. (JBD2_FEATURE_INCOMPAT_CSUM_V3)
345 Descriptor Block
348 The descriptor block contains an array of journal block tags that
351 described by a data structure, but here is the block structure anyway.
352 Descriptor blocks consume at least 36 bytes, but use a full block:
365 - Common block header.
369 - Enough tags either to fill up the block or to describe all the data
370 blocks that follow this descriptor block.
372 Journal block tags have any of the following formats, depending on which
373 journal feature and block tag flags are set.
375 If JBD2_FEATURE_INCOMPAT_CSUM_V3 is set, the journal block tag is
390 - Lower 32-bits of the location of where the corresponding data block
400 - Upper 32-bits of the location of where the corresponding data block
406 - Checksum of the journal UUID, the sequence number, and the data block.
431 - On-disk block is escaped. The first four bytes of the data block just
434 - This block has the same UUID as previous, therefore the UUID field is
437 - The data block was deleted by the transaction. (Not used?)
439 - This is the last tag in this descriptor block.
441 If JBD2_FEATURE_INCOMPAT_CSUM_V3 is NOT set, the journal block tag
456 - Lower 32-bits of the location of where the corresponding data block
461 - Checksum of the journal UUID, the sequence number, and the data block.
471 - This next field is only present if the super block indicates support for
472 64-bit block numbers.
476 - Upper 32-bits of the location of where the corresponding data block
492 JBD2_FEATURE_INCOMPAT_CSUM_V3 are set, the end of the block is a
506 - Checksum of the journal UUID + the descriptor block, with this field set
509 Data Block
513 are written verbatim into the journal file after the descriptor block.
514 However, if the first four bytes of the block match the jbd2 magic
516 flag is set in the descriptor block tag.
518 Revocation Block
521 A revocation block is used to prevent replay of a block in an earlier
524 block is freed and re-allocated as a file data block; in this case, a
525 journal replay after the file block was written to disk will cause
528 **NOTE**: This mechanism is NOT used to express “this journal block is
529 superseded by this other journal block”, as the author (djwong)
530 mistakenly thought. Any block being added to a transaction will cause
531 the removal of all existing revocation records for that block.
535 length, but use a full block:
548 - Common block header.
552 - Number of bytes used in this block.
558 After r_count is a linear array of block numbers that are effectively
559 revoked by this transaction. The size of each block number is 8 bytes if
560 the superblock advertises 64-bit block number support, or 4 bytes
565 block is a ``struct jbd2_journal_revoke_tail``, which has this format:
578 - Checksum of the journal UUID + revocation block
580 Commit Block
583 The commit block is a sentry that indicates that a transaction has been
584 completely written to the journal. Once this commit block reaches the
588 The commit block is described by ``struct commit_header``, which is 32
589 bytes long (but uses a full block):
602 - Common block header.
622 the entire commit block, with this field zeroed. If